The present invention relates to the forming of articles from liquid material that is both molded and cured to complete the article.
In the fabrication of many articles, a plastic resin or the like is molded or otherwise shaped while in a liquid or viscous state and is thereafter cured so as to harden the material and enable it to retain its molded configuration. Often, the plastic is initially heated to permit the same to be worked into its final form and the curing is thereafter effected by cooling. It is also known to utilize a construction material that is curable, as by polymerization, in response to irradiation by a beam of ultraviolet radiation or high energy electrons.
In conventional methods and apparatus for fabricating such articles, two discrete and individually identifiable steps of, first, molding or configuring the liquid material, and thence curing the same to a hardened state, are performed sequentially. For example, in the art of fabricating flexible plastic phonograph records which are often removably bound in magazines and the like for advertising or instructional purposes, a relatively thin sheet of plastic is initially heated in an oven-like environment so that the material becomes readily workable and selectively deformable. The heated plastic sheet is then conveyed or transported from the oven to a pressure mold at which the phonograph grooves are impressed onto the sheet.
Although the mold absorbs some heat from the plastic sheet and thereby aids in cooling the same, it is generally necessary to remove the sheet from the mold and convey it to a curing station where it is subjected to a cooling air flow so as to complete the hardening or curing of the plastic material. The process of flexible record fabrication is typically continuous so that the sheet of material is kept moving in assembly-line fashion from one station to the next. However, the plastic sheet must be moved at a relatively slow rate to enable the desired result to be attained at each station, and fabrication time for a completed article is consequently uneconomically lengthy. Continuous operation of the necessary heating and cooling apparatus also uses a significant amount of energy which contributes to relatively high article fabrication costs.
A further disadvantage of the known method is inherent in the movement of the article between the molding and curing stations. Since the construction material is still in an essentially liquid state after molding and prior to curing or hardening, the liquid material flows and undergoes varying amounts of distortion from its molded configuration as it is moved between the two stations. The amount of distortion which occurs generally depends upon the viscosity of the material and the nature or form of the molded article. Particularly in the fabrication of phonograph records, in which the precise depth and shape of the grooves determine the accuracy with which the stored information or sound can be reproduced, any deformation or distortion of the groove pattern initially impressed on the plastic sheet prior to curing is most undesirable. Yet, distortion is for the most part unavoidable in presently known methods of fabrication irrespective of whether the material is first heated and then cured by cooling, or is instead molded in a cool liquid state utilizing a radiation-curable material and thereafter hardened by irradiating the preconfigured liquid material.
It is, therefore, the desideratum of the present invention to provide a method and apparatus for the production of molded articles from a liquid material by which the articles can be fabricated at a relatively rapid rate with a minimum expenditure of energy while eliminating undesired distortion or deformation of the configuration imparted to the liquid material in the molding operation prior to curing or hardening thereof.
In particular, it is an object of the present invention to provide a method and apparatus for substantially instantaneous liquid molding of an article.
It is another object of the invention to provide a method and apparatus for substantially instantaneous molding and curing of a liquid material in the fabrication of an article therefrom.
A further object of the invention is the provision of a method and apparatus for substantially instantaneous liquid molding of articles on a continuous web of base material.